From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 8904B38DD4 for ; Wed, 20 Dec 2023 13:43:55 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="GYTxO7tC" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 53AEEC433C7; Wed, 20 Dec 2023 13:43:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1703079834; bh=QMljrOv897FmsVWy5N1Xz1hinrz7EiFYEPnIJAs7QUk=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=GYTxO7tCPod+y4rqctr2YHQpxphABVWY/4y3FiRw1JNEEv9Dan5eWkIViHB2JPSaG Dacl3Sbn3Q4HjTXCmizka1qqIj/bkNLFWROf49sEF/uEPpHC21Z34tehaxEPdSIVdB rwH4WthiRs3UBfVvqnRM/d0yTHuWZanyIWsZXeb/fdGFGZrusA1L4ukUnzUoXXm/0e EvZQj/pXAJ1+EH1V/qfhSfvDR+LmCsQN9sSNuvAe0eWzoE/cmIEyiHkoYU+gUhSlfJ oHxoX62pQIgCBmdaZSuI2QHWewuRVS6Gli+AWVXu6gqIfdlHGd4YKRVn6izE81kRm5 xAaEboEdJlS9w== Date: Wed, 20 Dec 2023 14:43:51 +0100 From: Frederic Weisbecker To: Anna-Maria Behnsen Cc: linux-kernel@vger.kernel.org, Peter Zijlstra , John Stultz , Thomas Gleixner , Eric Dumazet , "Rafael J . Wysocki" , Arjan van de Ven , "Paul E . McKenney" , Rik van Riel , Steven Rostedt , Sebastian Siewior , Giovanni Gherdovich , Lukasz Luba , "Gautham R . Shenoy" , Srinivas Pandruvada , K Prateek Nayak Subject: Re: [PATCH v9 05/32] tracing/timers: Add tracepoint for tracking timer base is_idle flag Message-ID: References: <20231201092654.34614-1-anna-maria@linutronix.de> <20231201092654.34614-6-anna-maria@linutronix.de> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20231201092654.34614-6-anna-maria@linutronix.de> Le Fri, Dec 01, 2023 at 10:26:27AM +0100, Anna-Maria Behnsen a écrit : > When debugging timer code the timer tracepoints are very important. There > is no tracepoint when the is_idle flag of the timer base changes. Instead > of always adding manually trace_printk(), add tracepoints which can be > easily enabled whenever required. > > Signed-off-by: Anna-Maria Behnsen Reviewed-by: Frederic Weisbecker Just a detail below, again this can be posted as a delta patch or edited before applying: > --- > v9: New in v9 > --- > include/trace/events/timer.h | 20 ++++++++++++++++++++ > kernel/time/timer.c | 2 ++ > 2 files changed, 22 insertions(+) > > diff --git a/include/trace/events/timer.h b/include/trace/events/timer.h > index 99ada928d445..1ef58a04fc57 100644 > --- a/include/trace/events/timer.h > +++ b/include/trace/events/timer.h > @@ -142,6 +142,26 @@ DEFINE_EVENT(timer_class, timer_cancel, > TP_ARGS(timer) > ); > > +TRACE_EVENT(timer_base_idle, > + > + TP_PROTO(bool is_idle, unsigned int cpu), > + > + TP_ARGS(is_idle, cpu), > + > + TP_STRUCT__entry( > + __field( bool, is_idle ) > + __field( unsigned int, cpu ) > + ), > + > + TP_fast_assign( > + __entry->is_idle = is_idle; > + __entry->cpu = cpu; > + ), > + > + TP_printk("is_idle=%d cpu=%d", > + __entry->is_idle, __entry->cpu) > +); > + > #define decode_clockid(type) \ > __print_symbolic(type, \ > { CLOCK_REALTIME, "CLOCK_REALTIME" }, \ > diff --git a/kernel/time/timer.c b/kernel/time/timer.c > index a81d793a43d0..46a9b96a3976 100644 > --- a/kernel/time/timer.c > +++ b/kernel/time/timer.c > @@ -1964,6 +1964,7 @@ u64 get_next_timer_interrupt(unsigned long basej, u64 basem) > if ((expires - basem) > TICK_NSEC) > base->is_idle = true; > } > + trace_timer_base_idle(base->is_idle, base->cpu); This will trigger a trace everytime we loop into idle or remotely compute the next timer. Can we move that to when base->is_idle is set from false to true only? > raw_spin_unlock(&base->lock); > > return cmp_next_hrtimer_event(basem, expires); > @@ -1985,6 +1986,7 @@ void timer_clear_idle(void) > * the lock in the exit from idle path. > */ > base->is_idle = false; > + trace_timer_base_idle(0, smp_processor_id()); Same here. If base->is_idle was already false, you could spare a noisy trace. Thanks. > } > #endif > > -- > 2.39.2 >